降钙素对卵巢切除大鼠骨转换的影响

Effect of calcitonin on bone turnover in ovariectomized Rats

尽管降钙素已在临床用于防治骨质疏松症，但其对骨转换的影响并未阐明，为此本实验以骨组织形态计量学为手段，观察了降钙素对卵巢切除大鼠小梁骨体积和骨转换的影响。实验分三组：卵巢切除后用降钙素组、卵巢切除后用生理盐水组和假手术组。取胫骨干骺端作不脱钙骨切片，行骨组织计量学测定。结果表明，与假手术组相比，卵巢切除后用生理盐水组其小梁骨体积明显下降，破骨细胞表面积、成骨细胞表面积、类骨质表面积、矿化表面积、矿化沉积率和骨形成率均明显升高。相反，卵巢切除后用降钙素组其小梁骨体积恢复正常，骨转换指标也接近假手术组。说明降钙素不仅抑制卵巢切除大鼠骨吸收，而且抑制其骨形成，使骨转换降低，从而预防卵巢切除大鼠骨丢失。

Objective: Although calcitonin has been used to treat osteoporosis clinically, its effect on bone turnover is still unclear. Therefore, the present study involves use of bone histomorphometry as a method to observe the effect of calcitonin on cancellous bone volume and bone turnover in ovariectomized(OVX) rats. Methods:24 female Wistar rats, 7-8 months old, were subjected to 3 groups: OVX and treated with salmon calcitonin (OVXsCT), OVX and treated with a vehicle(OVX-Veh) and sham operated and treated with a vehicle (control-Veh).5μm and 20-μm cross-sections of tibial diaphyses were made for bone histomorphometry measurements. Results: In comparison with control-Veh rats, the proximal tibia of OVX-Veh rats were characterized by decrease in cancellous bone volume and significant increase in osteoclast surface area, osteoblast surface area, osteoid surface area, mineralizing surface area, mineral apposition rate and bone formation rate. In contrast, OVX rats treated with sCT made recovery to normal cancellous bone volume and showed a significant decrease in all the indices of bone turnover to near control-Veh levels. Conclusion: Calcitonin depresses bone turnover and prevents the development of osteopenia in OVX rats.